The present invention relates to compositions for the processing of fruit and vegetables by thermal fogging, particularly in enclosures such as storage chambers or greenhouses.
The processing of fruits and vegetables after harvesting may be designed to ensure only protection during the period running from packaging to sale or to ensure also the preservation of the fruit and vegetables in cases where the fruit and vegetables are intended to be warehoused before sale.
In this second case, which is the most general case for apples and pears, potatoes and some other varieties of fruits and vegetables, a treatment is generally carried out on the products in the box.
For this purpose, the boxes are immersed in or sprayed with an aqueous solution containing the various chemical processing materials.
For treatment with insecticides, in the open air, there exist thermal fogging apparatuses which put into the form of a fine mist a liquid insecticide composition by injection of this composition into a hot gas at high speed.
The use of such apparatus to apply treatment substances in enclosures to fruits and vegetables could also be contemplated. However, difficulties are encountered when it is desired, in practice, to use this technique, since the fruit inside stored boxes is difficult to reach and to coat homogeneously. It is essential that the coating should be homogeneous in order that the protection may be correct and that the admissible limits for residues of active substances should not be exceeded. In addition, the substances used for treating fruits and vegetables are generally lipophile organic substances which are practically insoluble in water, often and are the solid state at ambient temperature. Now, the use of solutions in organic solvents for lipophile substances is hardly suitable by reason of the dangers of phytotoxicity, even in the case of careful ventilation of the sites in which the fogging is carried out. In addition, the use of a dispersion of conventional wettable powders does not give a homogeneous coating by reason of the particle size of these powders smaller than (1 micron).
It is an object of the present invention to provide compositions which can be applied by means of thermal fogging equipment, which does not leave dangerous residues in the enclosure where the thermal fogging is carried out and which permits the production of a regular coating on all fruits and vegetables in stored boxes, whatever their position in the storage chamber.
According to the present invention there is provided for this purpose a composition designed for the processing of fruits and vegetables by thermal fogging, characterised in that it comprises from 2 to 25% by weight of at least one active protective and/or preserving substance, in solution or in dispersion in an aqueous medium containing a mixture of at least two emulsifiers each having an HLB value of 3 to 20, this mixture having an average HLB value of 8 to 15 and the active substance, when it is solid and does not give a true solution in said medium, being in the form of particles of less than 1 micron.
By HLB value of the emulsifier, is meant the value of the hydrophile-lipophile balance. In the case of a non-ionic emulsifier, this value is equal to
% hydrophile portion by weight: 5. This weight is extrapolatable by similitude to anionic products. PA0 from 2 to 20% by weight (more preferably from 10 to 15% by weight) of active substance, PA0 from 10 to 20% by weight of water, PA0 from 25 to 50% by weight of glycol, and PA0 from 5 to 50% by weight of a mixture of emulsifiers having an average HLB value of 10 to 15. PA0 from 8 to 12% by weight of a fatty acid such as oleic acid, PA0 from 14 to 18% by weight of a salt of a fatty acid such as the potassium salt of oleic acid, and optionally, PA0 up to 30% by weight of a mixture of emulsifiers having an average HLB value of 8 to 15. PA0 antioxidants such as ethoxyquine, diphenylamine, butylhydroxyanisole, PA0 antigerminating agents, such as chlorophenyl isopropyl carbamate, PA0 fungicides such as thiabendazole, iprodione, sec.butylamine.
In a first embodiment, the composition according to the present invention comprises from 2 to 6% by weight of active substance, from 5 to 20% by weight of a mixture of at least two emulsifiers having an average HLB value to 8 to 15, the rest being water.
In a second and preferred embodiment of the invention, the composition according to the present invention comprises:
The glycol is advantageously propylene glycol, although other glycols such as ethylene glycol may be used.
As mixture of emulsifiers, the preferred composition comprises advantageously:
The mixture of fatty acid and of fatty acid salt may be obtained simply by mixing the fatty acid and a strong base. This mixture acts as a mixture of two emulsifiers, one with HLB of about 3 and the other with an HLB of about 20.
The preferred compositions have the advantage of possessing a reduced water content which permits at the same time the avoidance of two severe cooling of the gases in the thermal fogging apparatus and overheating of the active substances introduced into the thermal fogging apparatus.
The active substances for protection and/or preservation of the fruits and vegetables which are present in the composition according to the invention may be particularly
It is to be noted that there are obtained, according to the nature of the active substances, very stable dispersions or true solutions. These true solutions are generally obtained with substances which are liquid at ambient temperature and practically insoluble in water and obviously with water-soluble substances, as well as with certain solid substances which are themselves practically insoluble in water. The latter fact is particularly surprising. Thus, true solutions are obtained, particularly with ethoxyquine, butylhydroxyanisole, diphenylamine and chlorophenylisopropyl carbamate and dispersions with substances such as iprodione and thiabendazole.
The pH of the aqueous compositions according to the invention can be adjusted to a value of 6 to 8 so as not to spoil the fruits and vegetables treated.
In order that the invention may be more fully understood, a number of examples are described below, purely by way of non-limiting illustration.